Phaseout of Class II Ozone-Depleting Substances

“Class II” ozone-depleting substances (ODSHelpODSA compound that contributes to stratospheric ozone depletion. ODS include chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl bromide, carbon tetrachloride, hydrobromofluorocarbons, chlorobromomethane, and methyl chloroform. ODS are generally very stable in the troposphere and only degrade under intense ultraviolet light in the stratosphere. When they break down, they release chlorine or bromine atoms, which then deplete ozone. A detailed list ( of class I and class II substances with their ODPs, GWPs, and CAS numbers are available.) have an ozone depletion potentialHelpozone depletion potentialA number that refers to the amount of ozone depletion caused by a substance. The ODP is the ratio of the impact on ozone of a chemical compared to the impact of a similar mass of CFC-11. Thus, the ODP of CFC-11 is defined to be 1.0. Other CFCs and HCFCs have ODPs that range from 0.01 to 1.0. The halons have ODPs ranging up to 10. Carbon tetrachloride has an ODP of 1.2, and methyl chloroform's ODP is 0.11. HFCs have zero ODP because they do not contain chlorine. A table of all ozone-depleting substances ( shows their ODPs, GWPs, and CAS numbers. less than 0.2, and are all hydrochlorofluorocarbonsHelphydrochlorofluorocarbonA compound consisting of hydrogen, chlorine, fluorine, and carbon. The HCFCs are one class of chemicals being used to replace the CFCs. They contain chlorine and thus deplete stratospheric ozone, but to a much lesser extent than CFCs. HCFCs have ozone depletion potentials (ODPs) ranging from 0.01 to 0.1. Production of HCFCs with the highest ODPs are being phased out first, followed by other HCFCs. A table of ozone-depleting substances ( shows their ODPs, GWPs, and CAS numbers. HCFCs are numbered according to a standard scheme ( (HCFCs). HCFCs were developed as transitional substitutes for Class I ODS and are subject to a later phaseout schedule than Class I ODS.

HCFCs are used in a wide variety of applications, including refrigeration, air conditioning, foam blowing, solvents, aerosols, and fire suppression. Although there are currently 34 HCFCs that are subject to the phaseout, only a few are commonly used. Historically, the most widely used include HCFC-22 (usually as a refrigerant), HCFC-141b (as a solvent and foam-blowing agent), and HCFC-142b (as a foam-blowing agent and component in refrigerant blends). Learn more about common HCFCs and their uses.

Some HCFCs, like HCFC-22, are also a component in refrigerant blends. While these blends are not listed among the 34 controlled HCFCs, they are subject to the same rules because they contain Class II ODS. Common refrigerant blends that contain HCFC-22 include R-401A, R-402A, R-408A, R-409A, R-414B, and R-502A.

The Phaseout of HCFCs

Key Resource

Learn about the projected demand for HCFCs in existing air-conditioning and refrigeration equipment in EPA’s 2014 Final Report: Projected Servicing Needs in the U.S. Air-conditioning, Refrigeration, and Fire Suppression Sectors, Updated for 2015 to 2025

As a Party to the Montreal ProtocolHelpMontreal ProtocolThe international treaty governing the protection of stratospheric ozone. The Montreal Protocol on Substances That Deplete the Ozone Layer and its amendments control the phaseout of ODS production and use. Under the Montreal Protocol, several international organizations report on the science of ozone depletion, implement projects to help move away from ODS, and provide a forum for policy discussions. In addition, the Multilateral Fund provides resources to developing nations to promote the transition to ozone-safe technologies. The full text of the Montreal Protocol ( is available from the United Nations Environmental Programme (UNEP)., the United States must incrementally decrease HCFC consumption and production, culminating in a complete HCFC phaseout in 2030. HCFC usage must be reduced to at least 90 percent below baseline levels in 2015 and to at least 99.5 percent below baseline levels in 2020.

Section 605 of the Clean Air ActHelpClean Air ActA law amended by Congress in 1990. Title VI of the CAA ( directs EPA to protect the ozone layer through several regulatory and voluntary programs. Sections within Title VI cover production of ozone-depleting substances (ODS), the recycling and handling of ODS, the evaluation of substitutes, and efforts to educate the public. establishes the U.S. phaseout targets for Class II substances. In 1993, EPA established the phaseout framework and the "worst-first" approach, which focused first on HCFC-22, HCFC-141b, and HCFC-142b because they have the highest ozone depletion potentials of all HCFCs.

The U.S. schedule for meeting the Montreal Protocol phaseout requirements is summarized in the following table.

U.S. Action to Meet the Montreal Protocol Phaseout Schedule
Year to Be Implemented Implementation of HCFC Phaseout through Clean Air Act Regulations Year to Be Implemented Percent Reduction in HCFC Consumption and Production from Baseline
2003 No production or import of HCFC-141b 2004 35.0%
2010 No production or import of HCFC-142b and HCFC-22, except for use in equipment manufactured before January 1, 2010 2010 75.0%
2015 No production or import of any other HCFCs, except as refrigerants in equipment manufactured before January 1, 2020 2015 90.0%
2020 No production or import of HCFC-142b and HCFC-22 2020 99.5%
2030 No production or import of any HCFCs 2030 100.0%

More about the HCFC Allowance System

Common HCFCs and Their Uses

Common HCFCs include:

The phaseout restricts the use of these HCFCs, and EPA continues to evaluate HCFC alternatives through its Significant New Alternatives Policy (SNAP) program.